The Kingdom of Elleore is a micronation in Roskilde Fjord, in Denmark. It was established in 1944 by a group of schoolteachers, and despite its declaration of independence being something of a joke, the 'kingdom' has continued. The island has its own monarchs, flag, coins and stamps, and even its own time zone, twelve minutes behind Danish time.
You can visit Elleore's official website here (though it is in Danish) or read an entertaining article about the island micronation by clicking on the map below.